final l is always doubled in British
English (not in American English)

Example:

travel - travelled

after a consonant, final y becomes i
(but: not after a vowel)

Example:

worry - worried

but: play - played

Exceptions
when adding 'ing' :

silent e is dropped. (but: does not
apply for -ee)

Example: come
- coming
aber: agree - agreeing

after a short, stressed vowel, the final
consonant is doubled

Example: sit - sitting

after a vowel, the final consonant l is
doubled in British English (but not in American English).

Example: travel - travelling

final
ie becomes y.

Example: lie - lying

Use

Both tenses are used to express that an action began
in the past and is still going on or has just finished. In many cases, both
forms are correct, but there is often a difference in meaning: We use the Present
Perfect Simple mainly to express that an action is completed or to
emphasise the result. We use the Present Perfect Progressive to
emphasise the duration or continuous course of an action.

Result or
duration?

Do you want to express what has happened so far or how
long an action has been going on yet?

Present Perfect SimplE

Present Perfect Progressive

Result (what / how much / how often)

I have
written 5 letters. / I have been to London twice.

Duration (how long)

I have been
writing for an hour.

Certain verbs

The following verbs are usually only used in Present
Perfect Simple (not in the progressive form).

state: be, have (for possession only)

Example: We have
been on holiday for two weeks.

senses: feel, hear, see, smell, taste, touch

Example: He has
touched the painting.

brain work: believe, know, think, understand

Example: I have
known him for 3 years.

Emphasis on
completion or duration?

Do you want to emphasise the completion of an action
or its continuous course (how has somebody spent his time)?

Present Perfect Simple

Present Perfect Progressive

Emphasis on completion

I have done
my homework. (Meaning: My homework is completed now.)

Emphasis on duration

I have been
doing my homework. (Meaning: That's how I have spent my time. It does not
matter whether the homework is completed now.)

Result or side
effect?

Do you want to express that a completed action led to
a desired result or that the action had an unwanted side effect?

Present Perfect Simple

Present Perfect Progressive

desired result

I have washed
the car. (Result: The car is clean now.)

unwanted side effect

Why are you
so wet? - I have been washing the car. (side effect: I became wet when I
was washing the car. It does not matter whether the car is clean now.)

Time +
negation: last time or beginning of an action?

In negative sentences: Do you want to express how much
time has past since the last time the action took place or since the beginning
of the action?

Present Perfect Simple

Present Perfect Progressive

since the
last time

I haven't
played that game for years. (Meaning: It's years ago that I last played
that game.)

since the
beginning

I haven't
been playing that game for an hour, only for 10 minutes. (Meaning: It's
not even an hour ago that I started to play that game.)

Permanent or
temporary?

If an action is still going on and we want to express
that it is a permanent situation, we would usually use the Present Perfect
Simple. For temporary situations, we would prefer the Present Perfect
Progressive. This
is not a rule, however, only a tendency.

Present Perfect Simple

Present Perfect Progressive

permanent

James has
lived in this town for 10 years. (Meaning: He is a permanent resident of
this town.)

temporary

James has
been living here for a year. (Meaning: This situation is only temporary.
Maybe he is an exchange student and only here for one or two years.)